security: A01-13 — nest all event routes under organisation prefix

Move all authenticated organiser-facing event sub-resource routes from
/events/{event}/... to /organisations/{organisation}/events/{event}/...
to enforce multi-tenancy at the routing layer.

Changes:
- Routes: restructured api.php to nest all event sub-resources under
  the existing organisation prefix group
- Controllers: added Organisation parameter and VerifiesOrganisationEvent
  trait to all 12 affected controllers (sections, time-slots, shifts,
  persons, crowd-lists, locations, shift-assignments, registration-fields,
  availabilities, field-values, section-preferences, stats)
- Tests: updated all 20 feature test files with new route paths
- Frontend: updated 8 API composables and 20 Vue components/pages
- API.md: updated documentation to reflect new route structure

Portal routes, public routes (volunteer-register), and invitation routes
remain unchanged as they operate without organisation context.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/Http/Controllers/Api/V1/LocationController.php

@@ -5,19 +5,24 @@ declare(strict_types=1);
 namespace App\Http\Controllers\Api\V1;
 
 use App\Http\Controllers\Controller;
+use App\Http\Controllers\Api\V1\Traits\VerifiesOrganisationEvent;
 use App\Http\Requests\Api\V1\StoreLocationRequest;
 use App\Http\Requests\Api\V1\UpdateLocationRequest;
 use App\Http\Resources\Api\V1\LocationResource;
 use App\Models\Event;
 use App\Models\Location;
+use App\Models\Organisation;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Resources\Json\AnonymousResourceCollection;
 use Illuminate\Support\Facades\Gate;
 
 final class LocationController extends Controller
 {
-    public function index(Event $event): AnonymousResourceCollection
+    use VerifiesOrganisationEvent;
+
+    public function index(Organisation $organisation, Event $event): AnonymousResourceCollection
     {
+        $this->verifyEventBelongsToOrganisation($organisation, $event);
         Gate::authorize('viewAny', [Location::class, $event]);
 
         $locations = $event->locations()->orderBy('name')->get();
@@ -25,8 +30,9 @@ final class LocationController extends Controller
         return LocationResource::collection($locations);
     }
 
-    public function store(StoreLocationRequest $request, Event $event): JsonResponse
+    public function store(StoreLocationRequest $request, Organisation $organisation, Event $event): JsonResponse
     {
+        $this->verifyEventBelongsToOrganisation($organisation, $event);
         Gate::authorize('create', [Location::class, $event]);
 
         $location = $event->locations()->create($request->validated());
@@ -34,8 +40,9 @@ final class LocationController extends Controller
         return $this->created(new LocationResource($location));
     }
 
-    public function update(UpdateLocationRequest $request, Event $event, Location $location): JsonResponse
+    public function update(UpdateLocationRequest $request, Organisation $organisation, Event $event, Location $location): JsonResponse
     {
+        $this->verifyEventBelongsToOrganisation($organisation, $event);
         Gate::authorize('update', [$location, $event]);
 
         $location->update($request->validated());
@@ -43,8 +50,9 @@ final class LocationController extends Controller
         return $this->success(new LocationResource($location->fresh()));
     }
 
-    public function destroy(Event $event, Location $location): JsonResponse
+    public function destroy(Organisation $organisation, Event $event, Location $location): JsonResponse
     {
+        $this->verifyEventBelongsToOrganisation($organisation, $event);
         Gate::authorize('delete', [$location, $event]);
 
         $location->delete();